Swab for collecting biological specimens

ABSTRACT

The present invention relates to a swab for collecting biological specimens of the type consisting of a rod terminating in a tip covered with fiber with hydrophilic properties to allow absorption of said specimens, wherein said fiber covers said tip in the form of a layer deposited by flocking.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a continuation of and claims the benefit of priorityto U.S. patent application Ser. No. 13/899,394, filed on May 21, 2013,which is a continuation of U.S. patent application Ser. No. 13,361,584,filed on Jan. 30, 2013, now Issued U.S. Pat. No. 8,979,784, which is acontinuation of Ser. No. 10/543,873, filed on Jul. 28, 2005, now IssuedU.S. Pat. No. 8,114,027, which is a U.S. 371 National Phase Applicationof International Application No. PCT/EP2004/003392, filed on Mar. 31,2004, which claims priority to Italian Application No. MI2003A000643,filed on Apr. 1, 2003.

FIELD OF THE INVENTION

The present invention relates to a swab for collecting biologicalspecimens.

BACKGROUND OF THE INVENTION

In the field of clinical and diagnostic analyses, swabs for collectingbiological specimens of organic material are known, consistingessentially of a cylindrical rod around one end of which, known as thetip, is wrapped a wad of fibre such as rayon or a natural fibre such ascotton, with hydrophilic properties to allow rapid absorption of thequantity of specimen to be collected and tested. Stable adherence of thefibre wrapped around the tip of the rod is generally achieved by gluing.

Usually, especially if the specimen is to be examined by culturing themicroorganisms gathered with the collection, a swab is immersed in atest-tube containing culture medium immediately after collection forappropriate conservation of the specimen during storage and/or transportthereof to the analytical laboratory.

An example of this type of device is given in patent EP0643131 by thesame Applicant and refers to a swab for collecting and in vitrotransporting specimens, of the type comprising a test-tube with culturemedium in gel form and a rod carrying at one end a stopper for sealingthe test-tube and at the opposite end means for collecting saidspecimen, for example a wad of fibre wrapped around the tip of the rod,to be dipped into the culture medium.

The tip of the cylindrical rod, generally manufactured from essentiallyrigid material such as plastic, for example by extrusion, commonlypresents a truncating cut which would make it difficult to insert theswab rod into the cavities {oral, nasal, ocular or rectal, urethral,vaginal etc.) of the patient from whom the specimen is taken, if the tipis not adequately protected. Therefore, the wad of hydrophilic fibrewrapped around said truncated end must not only contain sufficientmaterial to allow absorption of the specimen in the desired quantity, ingeneral 100 microliters, but must also have a sufficiently thick androunded shape to sheathe the edge of the truncated end so that it cannotcause damage or irritation to the patient during specimen collection.For this reason the fibre wad is wrapped around the tip of the rod in arounded shape, typically developing into an ogive or similar shape sothat it gradually becomes thicker towards the end of the rod thusreaching maximum thickness and therefore maximum protective effect,precisely around the truncated end. A wad of such a shape, whileprotecting the patient from any risk of contact with said truncated endof the rod, results in a number of drawbacks. The main one is that thethickness of the wad, because of the hydrophilic nature of the fibre,leads to penetration of collected liquid specimen into the mass of saidwad. As, for practical reasons, the sample is released from the swab atthe moment of analysis by simply gripping the rod of the swab anddelicately sliding its tip and hence the fibre impregnated with liquid,along for example a petri dish with culture medium, in practice byspreading the specimen onto this latter (swabbing), even if thisoperation is repeated and is careful, it does not enable the entirevolume e.g. the 100 ml of absorbed specimen to be released, because thatpart of it which has penetrated into the interior of the wad in thedirection of its tip cannot be pressed out towards the surface and hencereleased by the swab during this operation

Due to this defect, on average only about 40% of the liquid specimencollected can in practice be recovered for analysis. Such loss ofspecimen translates inevitably into reduced sensitivity of analysis andincreased false negatives. In this respect, referring to theaforementioned average specimen loss after swabbing the swab, by testingonly the 40 microliters released for swabbing out of the 100 microlitersof specimen initially collected, it becomes difficult to establishwhether a negative test effectively refers to the absence of themicroorganism sought or rather to its non- or insufficient transfer fromswab to test plate.

A further problem derived from the bulky fibre wad of a swab of theknown art is particularly evident for example in the case of urethral orocular use of said swab. In these and other particular applications itwould actually be even more desirable to be able to minimize swabthickness and hence patient discomfort during collection.

SUMMARY OF THE INVENTION

As a solution to these problems, and also to achieve other advantageswhich will be apparent from the description, the present inventionproposes a swab for collecting biological specimens of the typeconsisting of a rod terminating with a tip covered in fibre withhydrophilic properties to allow absorption of said specimens,characterised in that said fibre covers said tip in the form of a layerapplied by means of flocking.

With the aim of better understanding the characteristics and advantagesof the invention, a non-limiting example of a practical embodimentthereof is described hereinafter, with reference to the figures of theaccompanying drawings. Said example refers to the case of a swabsuitable for both the collection and storage of a biological specimen,and therefore also includes a test-tube containing a culture mediumsuitable for the collected microorganisms into which the swab is to beimmersed after collection, such as for example the type described in theaforementioned patent EP0643131 by the same Applicant.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an exploded view of the two components of a device inaccordance with the example, that is the swab and test-tube, whereby thetest-tube is partially sectioned longitudinally.

FIG. 2 shows an enlarged detail of the swab of FIG. 1 in section.

DETAILED DESCRIPTION OF THE INVENTION

With reference to said figures, a device of the invention in accordancewith the illustrated example comprises an essentially cylindricaltest-tube containing a culture medium in gel form 11, presenting a freesurface level 12 inside the test-tube.

The upper open end of the test-tube presents a collar 13 for receiving aclosure means.

The device is completed by a swab 20 consisting of a rod 14 carrying atone end a stopper 15 which has to act as the closure means of thetest-tube and is hence shaped so that it can engage, for example bysnap-engaging, with the collar 13 of the test-tube.

At the opposite end, the rod 14 terminates with a tip 16 carrying asuitable means, for example a layer of fibre 17, for collecting thespecimen to be analysed. In the illustrated example, said tip 16 of therod is shaped in a rounded geometry, similar to an ogive, and said fibre17 being disposed as a layer of uniform thickness.

In general terms, in accordance with the fundamental characteristic ofthe invention, said fibre with hydrophilic properties is deposited bymeans of flocking. The flocking technique is preferably of the typeconducted in an electrostatic field which deposits the fibres in anordered manner, perpendicular to the surface of the tip of the swab rod,which has been previously coated with adhesive for example by immersionor spraying.

The fibre which is to form the flocked layer is subjected to anelectrostatic field, and is hence deposited in an oriented manner andanchored to the surface of the tip, being retained by the adhesive.

The adhesive is preferably water-based: once dried it enables the fibreto be anchored in a stable manner to the swab and to resist abrasion.

The flocked swab is then dried by exposing it to a source of heat orradio-frequency.

The tip of the swab stem is covered with a layer of fibre, preferably ofuniform thickness, and from 0.6 to 3 mm thick. The fibre count, i.e. theweight in grams per 10,000 linear meters of a single fibre, ispreferably between 1.7 and 3.3 Dtex. In particular, a fibre of 0.6 mmlength and 1.7 Dtex can be applied by flocking to obtain a fine nap, anda fibre up to 3 mm in length and 3.3 Dtex can be applied to obtain along nap, obtaining, for values intermediate between the aforedefined,corresponding intermediate characteristics of thickness and fineness ofthe flocked layer.

Within the wide choice of such values, the expedient to be respectedaccording to the objects of the invention is to maintain an orderedarrangement of the fibres, substantially parallel to each other andnormal to the surface of the rod, avoiding any overlapping of fibreswhich can occur if the nap is too long. Indeed, in this manner thecapillary represented by each fibre, by virtue of which it can carry outits task of absorbing and releasing essentially the same quantity ofspecimen, remains unimpaired and functional.

The amount of fibre to be deposited for forming the flocked layer inaccordance with the invention is determined on the basis of the type offibre and the pre-chosen layer characteristics of thickness andfineness, in such a manner as to enable 100 microliters of specimen tobe absorbed.

In accordance with the objects of the invention, the fibre is chosenfrom a wide range of materials provided they are hydrophilic bycapillarity, such as for example, synthetic or artificial materials e.g.rayon, polyester, polyamide, carbon fibre or alginate, natural materialse.g. cotton and silk, or mixtures thereof.

EXAMPLES

Some preparative examples are now given of a swab according to theinvention.

Such examples are not intended in any way to limit the scope of theinvention.

Example 1

A swab is prepared using a plastic rod, suitable for human clinicalcollection, of diameter 2.5 mm which decreases to 1 mm over a length ofabout 6 cm.

The tip of the part with the smallest diameter is dipped in or sprayedwith an adhesive, then the rod is placed vertically in a flockingapparatus in electrostatic field to deposit a polyamide flock.

The polyamide flock of 0.7 mm length and 1.7 Dtex allows 0.5 μl per mm²to be absorbed, therefore by flocking the 10 mm long tip of said rod theabsorbing capacity obtained is 40 μl.

Example 2

Proceeding as per example 1, a rod with a spatulate end is used, suitedfor example to collecting organic specimens from the oral cavity of apatient.

Polyester fibre of 1 mm length and 1.7 Dtex count are used for theflocking.

Example 3

Proceeding as per examples 1 and 2, polyester fibre of 2 mm length and2.5 Dtex count is used.

Continuing in general terms, it is calculated that a swab of theinvention is capable of releasing about 90% of the absorbed specimen byswabbing, in this manner considerably increasing the sensitivity of theanalysis compared with swabs of the known art, in particular by almostcompletely eliminating the risk of false negatives resulting from theincomplete release of the collected specimen from swab to test plate.

In addition, the fact of being able to form, according to the invention,a fibre layer of any thickness, even very small, around the tip of therod rather than a mass to cover it, as in the known art, means that therequired rounded shape of the swab, i.e. free of edges, no longer has todepend on the mass of fibre itself but on the tip of the rod, which cantherefore be preferably shaped into a round form, as indeed occurs Inthe aforedescribed example and shown in the accompanying drawings.

Particularly in specific cases where swabs of the greatest possiblethinness are required, for example urethral or ocular, this represents afurther definite advantage over known swabs. Indeed a swab can beprovided with a rounded tip by virtue of its shaping, around which athin layer of fibre is deposited by flocking to allow on the one handcollection of a sufficient quantity of specimen for analysis, and on theother to minimize the total bulk of the part of the swab which is topenetrate the urethra, in consequence so reducing the discomfort of thepatient undergoing the collection procedure.

The shape given to the tip of the swab nevertheless varies greatlyaccording to the type of collection it is intended for, and can even betruncated or have edges when the type of collection (for example oral)allows it.

According to the invention, the type of adhesive, type of fibre andfibre characteristics, such as length and count, are in any case chosenfrom a wide range of options in order to obtain an ideal specific markerfor identifying the microbiological specimen, whether by a directdiagnostic technique, by immune-test, or by molecular biology techniquessuch as PCR, or with other known culturing, enrichment or selectiontechniques.

The specimen to be collected with a swab of the invention generallyconsists of bacteria or viruses or DNA or RNA or a mixture thereof.

The invention claimed is:
 1. A biological specimen collection swabconfigured for collecting biological specimen to be analyzed, the swabcomprising: a rod, terminating in a tip; and a layer of fibers whichwere disposed on a surface of the tip by flocking in an oriented mannerin an electrostatic field, the layer of fibers having a thickness of 0.6to 3 mm and being configured to have capillarity hydrophilic propertiesand configured to be capable of absorbing at least a quantity of 40 μlof liquid in the layer of fibers on the tip of the rod.
 2. The swabaccording to claim 1 wherein said layer of fibers is configured to becapable of absorbing at least a quantity of 100 μl of liquid in thelayer of fibers on the tip of the rod.
 3. The swab according to claim 1wherein said layer of fibers is configured to absorb said specimen bycapillarity effect.
 4. The swab according to claim 1 wherein said layerof fibers has an amount of fibers capable of absorbing said quantity ofliquid.
 5. The swab according to claim 1 wherein said fibers definecapillaries conferring hydrophilic properties to the layer of fibers bycapillarity.
 6. The swab according to claim 1 wherein said layer offibers was disposed on the surface of the tip by a flocking technique inwhich the fibers were deposited in an ordered manner on the tip of therod.
 7. The swab according to claim 1 wherein said layer of fibers wasdisposed on the surface of the tip by a flocking technique in which thefibers were deposited perpendicularly to the surface of the tip of therod.
 8. The swab according to claim 1, wherein said layer of fibers isdirectly deposited on a surface of said tip and/or wherein the layer offibers covers the tip of the rod.
 9. The swab according to claim 1wherein said fibers have a length of 0.6 to 3 mm.
 10. The swab accordingto claim 1, wherein said layer of fibers has a fiber count of 1.7 to 3.3Dtex.
 11. The swab according to claim 1, wherein said rod is a plasticrod and wherein the tip of the rod is rigid.
 12. The swab according toclaim 1, wherein said rod is a plastic rod and has a diameter from 1 mmto 2.5 mm.
 13. The swab according to claim 1, wherein the fibers aremade of polyester and/or polyamide.
 14. A method of collecting aspecimen comprising liquid by using a swab according to claim 1, themethod comprising the step of collecting a specimen by absorbing aquantity of at least 40 μl of said liquid in said layer of fibersdisposed on the tip of the rod.
 15. The method of claim 14 in which atleast 100 μl of said liquid is absorbed in said layer of fibers disposedon the tip of the rod during said step of collecting a specimen.
 16. Themethod of claim 14 in which said liquid is absorbed in said layer offibers on the tip of the rod by capillarity effect during said step ofcollecting a specimen.
 17. The method according to claim 14 furthercomprising steps of storing and transporting said quantity of specimenin said layer of fibers and/or a step of releasing said quantity ofspecimen from said layer of fibers and/or a step of analyzing saidquantity of specimen.
 18. A biological specimen collection swabconfigured for collecting biological specimen to be analyzed, the swabcomprising: a rod, terminating in a tip; and a layer of fibers whichwere disposed on a surface of the tip by flocking in an oriented mannerin an electrostatic field, the fibers having a length of 0.6 to 3 mm andthe layer of fibers being configured to have capillarity hydrophilicproperties and configured to be capable of absorbing at least a quantityof 40 μl of liquid in the layer of fibers on the tip of the rod.
 19. Theswab according to claim 18 wherein said layer of fibers is configured tobe capable of absorbing at least a quantity of 100 μl of liquid in thelayer of fibers on the tip of the rod.
 20. The swab according to claim18, wherein said layer of fibers has a fiber count of 1.7 to 3.3 Dtex.21. The swab according to claim 18, wherein said rod is a plastic rodand wherein the tip of the rod is rigid.